A common blood test is a routine blood test. When analyzing the routine blood test: the first step is to see whether the number of white blood cells is within the normal reference value, and also to see whether the number and ratio of the five types of white blood cells are within the normal reference value. If the number of leukocytes is abnormally high, with a significant increase in neutrophils, and the patient has local symptoms such as fever, this is likely to be an acute infection causing an increase in leukocytes. The second step is to look at the white blood cells to see if the red blood cell count, hemoglobin concentration and red blood cell pressure are within the normal range. If the number of red blood cells, red blood cell pressure and hemoglobin concentration are significantly lower, it indicates anemia, and the average volume of red blood cells, average hemoglobin volume and average hemoglobin concentration should also be looked at. The last item also depends on whether the number of platelets is within the normal range.